/**
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements.  See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership.  The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with the License.  You may obtain
 * a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package org.apache.zookeeper.graph.servlets;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.simple.JSONObject;
import org.json.simple.JSONValue;

import java.util.Map;

abstract public class JsonServlet extends HttpServlet {
    abstract String handleRequest(JsonRequest request) throws Exception;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/plain;charset=utf-8");
        response.setStatus(HttpServletResponse.SC_OK);

        try {
            String req = request.getRequestURI().substring(request.getServletPath().length());

            response.getWriter().println(handleRequest(new JsonRequest(request)));
        } catch (Exception e) {
            JSONObject o = new JSONObject();
            o.put("error", e.toString());
            response.getWriter().println(JSONValue.toJSONString(o));
        } catch (java.lang.OutOfMemoryError oom) {
            JSONObject o = new JSONObject();
            o.put("error", "Out of memory. Perhaps you've requested too many logs. Try narrowing you're filter criteria.");
            response.getWriter().println(JSONValue.toJSONString(o));
        }
    }

    protected class JsonRequest {
        private Map map;

        public JsonRequest(ServletRequest request) {
            map = request.getParameterMap();
        }

        public long getNumber(String name, long defaultnum) {
            String[] vals = (String[]) map.get(name);
            if (vals == null || vals.length == 0) {
                return defaultnum;
            }

            try {
                return Long.valueOf(vals[0]);
            } catch (NumberFormatException e) {
                return defaultnum;
            }
        }

        public String getString(String name, String defaultstr) {
            String[] vals = (String[]) map.get(name);
            if (vals == null || vals.length == 0) {
                return defaultstr;
            } else {
                return vals[0];
            }
        }
    }
}
